To examine the permeation rate of encapsulated material through an oil phase in W/O/W emulsions, permeation experiments of inorganic salts and ampholites through the oil phase were carried out in a W/O emulsion mixture system. Inorganic cations permeated through the oil phase, while inorganic anions did not. The permeation rate was expressed by a kinetic equation based on the concentration gradient between the different internal aqueous phases as a driving force. The overall mass transfer coefficient of inorganic cations was increased by increasing the concentration of surfactant, tetraglycerin-condensed ricinolate (TGCR) in the range of 2.0 to 15.0 wt%. It was found that TGCR became the carrier for the transportation of cations. Furthermore, positively charged ampholites permeated, but negatively charged ampholites did not. The overall mass transfer coefficient of positively charged ampholites decreased with increase in their molecular weight.

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Microgravity experiments on square two-component heat pipes made of Pyrex glass were carried out by utilizing the parabolic flight of an airplane for investigating Marangoni flow. Temperature variation in the heat pipes accompanying change in gravity level was principally dependent upon the distribution of working liquid. Although the liquid fill charge in the cooling section was increased abruptly by intermittent boiling, it later decreased at an almost constant rate except in the case of a relatively high concentration of initial mixture, such as 50 mol%. Comparison of liquid flow rates calculated from image data for the cooling section and liquid flow rates estimated from previous theory confirmed that the flow-back of working liquid induced by the Marangoni effect occurs by the predicted mechanism. It was also shown that the mechanism by which the working liquid is attached to the container wall was able to operate, and reformation of a liquid plug could be prevented, by use of square heat pipes; and that the application of the Marangoni effect is effective for generally used micro heat pipes.

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The relationships between the Marangoni effect and conditions of heat pipes, such as dimensions, heat transfer rate, initial concentration of working liquid and temperature of the cooling water, were investigated by considering the heat and mass transfer in two-component heat pipes. It was found that temperature and concentration gradient on the liquid-vapor interface becomes larger near the entrance of the cooling section, where the boundary layers of temperature and concentration were not fully developed. It was also found that in utilizing the Marangoni effect for flowback of the working liquid, it is preferable that the Marangoni number increases in the section in which the quantity of liquid for flowback increases. It was also shown that the condensate thickness does not necessarily became larger from the cooling edge to the entrance and is usually less than 0.3 mm for typical heat pipes, which is acceptable for wickless heat pipes. These results can not be explained by a simple model in which the effect of mass diffusion in the vapor phase is neglected.

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An experimental study was carried out to clarify the effect of viscosity on the flow characteristics of solid-liquid mixtures flowing through a vertical pipe. Spherical glass beads (0.19-2.2 mm in diameter) were suspended in upward flows of aqueous solutions of glycerol (2.97×10^-3-2.51×10^-2Pa·s in viscosity) or water (1.14×10^-3Pa·s in viscosity), and pressure drops were measured under various operating conditions. As a result, the solid-liquid mixture flow was found to show the transition from laminar to turbulent flow at lower velocity than the critical velocity for single-phase flow. This fact was confirmed by experiments of flow visualization and by pressure fluctuation measurement.
A plot of friction factor vs. Reynolds number was examined to express the effect of liquid viscosity on pressure drop of the mixture flow. A good correlation between these parameters was obtained by adopting the superficial velocity of the liquid as the characteristic velocity. Critical Reynolds numbers for the flow of mixtures with different concentrations and sizes of particles were extracted from the plots and expressed by a simple empirical equation. Moreover, correlation equations of friction factor were proposed separately for laminar and turbulent flow regions.

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The solid-based coordinate, which is useful for auto-matic treatment of shrinkage due to evaporation of solvent, may include a maximum value of diffusivity in a desorption (isothermal drying) process with a high initial solvent concentration. Here, a method for calculation of (integral diffusivity)/(desorption rate×efficiency) in such cases is presented, based on the integral form of the diffusion equation with the solid-based coordinate, using two empirical correration equations: 1) the relation between the 1st moment and the zero moment of concentration distribution, 2) the estimation equation for the ratio of average to center concentration from desorption rate master curves. Both (integral diffusivity) and (desorption rate×efficiency) are constant in the penetration period. The ratio of the two decreases monotonously with center concentration to a constant value of 0.65 in the last stage of the regular regime. The ratios at the end-point of the penetration period and in the regular regime are presented by empirical equations and in figures as functions of the ratio of average to center concentration. The diffusivity and the mutual diffusion coefficient can be calculated as a function of concentration, by differentiation of plots of (integral diffusivity) vs. (center concentration), obtained from desorption data of various initial concentrations with a constant surface concentration.
The numerical solutions of the diffusion equation were used for derivation and confirmation of the above calculation method, using various actual systems besides power and exponential models. As actual systems with empirical concentration-dependent diffusivities that have a maximum diffusivity, a food aqueous solution of sucrose and polymer-solvent solutions such as PVA-water, polystyrene-ethylbenzene, polyimide-parachlorophenol were used.

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Horizontal heated cylinders were placed at equal intervals to constitute 3×3 and 3×5 in-line arrangements, and natural convection heat transfer of the arrangements was experimentally investigated in air.
Average and local heat transfer coefficients of central vertical array were measured to extract representative heat transfer characteristics of each arrangement. Each heat transfer coefficient was expressed well by using the previously reported correlation methods for a vertical single array (Tokanai et al., 1997) and a horizontal single array (Kuriyama et al., 1995).

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Methylmercaptan (MM) gas was continuously treated in four systems: (i) an ultraviolet (UV) lamp system, (ii) a sheet material with titanium dioxide supported on fiber-activated carbon (FAC/TiO₂ sheet) with UV-irradiation system, (iii) a FAC/TiO₂ sheet system, and (iv) a sheet material with titanium dioxide supported on fiber without activated carbon (TiO₂ sheet) with UV-irradiation system, in order to clarify the sulfur balance and the effects of fluctuation of MM load in the continuous treatment of MM using photocatalyst supported on FAC. The sulfur balance in each system was accounted for by MM, dimethyl disulfide (DMDS), sulfur dioxide, and methane sulfonic acid. Although approximately 100% of MM was removed in the UV, FAC/TiO₂/UV, and TiO₂/UV systems, there were differences in the production of DMDS, a malodor compound. As the concentration of MM in the inlet gas increased, the production ratio of DMDS in the UV and TiO₂/UV systems became higher than in the FAC/TiO₂/UV system. These results indicate that the FAC/TiO₂/UV system has a higher capacity to deodorize MM than the UV and TiO₂/UV systems.

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This study was conducted to investigate solid-liquid reactions with phase transfer catalysts in an anhydrous system. The halogen exchange between benzyl chloride in the organic phase and potassium bromide (KBr) in the solid phase was carried out at 323 K or 353 K, and the esterification between benzyl chloride and sodium benzoate was carried out at 353 K. Polyethylene glycols with various molecular weights were used as catalysts. When these two reactions were carried out in an anhydrous system, a liquid phase containing polyethylene glycol was formed between the organic liquid phase and the solid phase.
The rate of halogen exchange without water was 18 times higher than that with water. In addition, a much smaller amount of KBr was required without water than with water. The reaction rate without water was maximal when the polyethylene glycol had an average molecular weight of 400. This phenomenon could be explained by the increase in solubility of benzyl chloride in polyethylene glycol and the decrease in that of KBr with the increase in the molecular weight of polyethylene glycol.
The rate of esterification without water was 9 times higher than that with water and was maximal with polyethylene glycol with an average molecular weight of 200.
In conclusion, these two reactions in a solid-liquid system without water occurred by the liquid reactant in the organic phase and the solid reactant being dissolved in a liquid phase containing polyethylene glycol.

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Biodegradable microcapsules entrapping an activated carbon impregnated with potassium nitrate were prepared by the solvent evaporation method in a (solid/oil/water) complex emulsion system. Biodegradable poly-ε-caprolactone (PCL) was used as a wall material. The effects of the PCL concentration and the weight fraction of the activated carbon on the morphology of the microcapsules prepared and the entrapment efficiency of potassium nitrate were investigated. On increasing the PCL concentration, the surface of the microcapsules became smoother, the voids formed inside decreased, and the fraction of potassium nitrate entrapped in the microcapsules increased. The entrapment also increased with the weight fraction of the activated carbon and reached a constant value at 2.5 wt%. By using the activated carbon impregnated with potassium nitrate as a core material, the amount of potassium nitrate entrapped in the microcapsules increased, and relatively high entrapment efficiency was maintained.

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Nitrogen and oxygen adsorption properties of Li, Na, K, Mg, Ca, or Sr ion-exchanged LSX zeolite (X zeolite with Si/Al=1.0) were investigated. Adsorption of nitrogen and oxygen tended to increase with an increase in the polarizing power of the ion. However, adsorption on MgLSX was much lower than would be expected from this tendency, because Mg93%LSX structure collapsed during the dehydration at 623 K, and Mg at site II in Mg62%LSX did not function as a strong adsorption site owing to its small ionic radius. LiLSX had the highest effective nitrogen adsorption and separation factor of nitrogen and oxygen at room temperature and atmospheric pressure, so LiLSX is considered for the best adsorbent for oxygen-PSA. The effective nitrogen adsorption and separation factor of NaLSX tended to approach those of LiLSX at lower temperature or higher pressure, and those of CaLSX tended to approach those of LiLSX at higher temperature or lower pressure. It is concluded that the effective nitrogen adsorption and separation factor varied with temperature and pressure owing to the effect of the polarizing power of the ions and the number of main adsorption sites.

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Experiments to separate nickel and chromium were carried out at 298 K on a porous glass packed-column using citric acid as an eluent. With increases in citric acid concentration in the eluent and in pH, the retention volume of both metals decreased, and the degree of overlap of the elution curves increased, due to the elution effect of secondary dissociated citric acid ion. With decrease in the particle diameter of the packing material, the elution curve narrowed and the degree of overlap of the elution curves decreased considerably, but the void volume in the column and the retention volume of both metals hardly changed. When porous glass powder of 100-200 mesh was packed in a column of 300 mm in length, nickel and chromium were eluted isocratically by 30 cm³ or less eluent containing 0.025-0.030 mol/dm³ of citric acid at pH 3.5, and a degree of overlap of 4-6% was obtained. Then, it was shown that the elution time can be remarkably shortened by using citric acid rather than acetic acid as an eluent.

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The total pressure drop in a multi-compartment bag filter was analyzed both theoretically and numerically with the patched cleaning model that the filter cloth just after cleaning consists of two surface areas, i.e., the area with residual dust and the perfectly cleaned area. The theoretical equation of the pressure drop with the fraction of perfectly cleaned filter cloth area ε_c=0.3 was derived over any operation time. By comparing the pressure drop calculated from the theoretical equation with that simulated numerically, a correction term was added to the theoretical equation of the pressure drop. The four parameters in the theoretical equation were correlated both theoretically and empirically so that the pressure drop could be estimated from the modified equation without the simulation procedure. A simplified equation without four parameters for the total pressure drop was obtained by comparison of the results of the theoretical equation with the numerical simulations. The simplified equation can reproduce well the total pressure drop over the operation time within the permitted error. The simplified equation derived for ε_c=0.3 can estimate well the pressure drop for the range of 0.15<ε_c<0.45 over the operation time.

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A new heat-balance model at a low air ratio of 0.2-0.5 has been developed. Prediction of bed temperature and gas temperature at the furnace outlet is important in designing a fluidized bed gasification furnace. Heat-balance models based on complete combustion are widely used to evaluate waste incineration plants. It is, however, impossible to apply these models to a fluidized bed gasification furnace because it is operated at low air ratio of 0.2-0.5. In this work, the effect of water content and air ratio on furnace temperature, gas composition and char yield were investigated using a 1 t/d-scale test facility. The bed and gas temperature were calculated to evaluate the validity of proposed model. By comparing calculated results with experimental data obtained in a 4.5 t/d test facility using another type of RDF, it was concluded that bed temperature and gas temperature at the furnace outlet could be predicted with satisfactory precision.

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Batchwise concentration and partial demineralization of skim milk were performed by nanofiltration up to 1/3.22 times the original volume, and the major salt flux data were analyzed using the extended Nernst-Planck equation.
The following observed rejections of major salt elements during nanofiltration were obtained: Na and K, 55-65%; Cl,11.5% at the start of nanofiltration, −85.2% at the end of nanofiltration; Ca and Mg, >98%; P, >97%. The reduction rates of Na, K and Cl were 56.6, 57.7 and 79.4% respectively.
The subsequent analysis was based on two assumptions: 1) the membrane completely rejects solutes other than Na, K and Cl; 2) the membrane carries a fixed charge due impermeable ions such as proteines in the retentate. Rejections of Na, K and Cl calculated from the analysis were good agreement with the experimental data.

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The continuous fermentation of L-lactic acid by Rhizopus oryzae AHU6537 was attempted with dilution rate of 0.02 h^-1 and feed glucose rate of 2.0 kg/(m³·h) in an airlift bioreactor. As a result, stable operation could be carried out over a long time without immobilizing cells. When the optimum amount of yeast extract in batch culture was added to the starting medium, the cells formed spherical pellets, and the fermentation rate was improved. Further, to investigate the influence of glucose and lactic acid concentration, when the dilution rate and glucose concentration in feed medium were controlled in continuous fermentation, it was found that R. oryzea was strongly inhibited by the lactic acid produced. When the effect of lactic acid inhibition was analyzed according to a Michaelis-Menten mechanism with uncompetitive inhibition and the fermentation rate at the steady state was simulated, the calculated lines agreed well with experimental values.

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We investigated the refolding of protein in inclusion bodies using reversed micelles formed by aerosol OT (AOT). RNase A was overexpressed in E. coli and used to prepare inclusion bodies of RNase A, which were then subjected to protein refolding by the AOT/isooctane reversed micellar system. The RNase A was renatured in reversed micelles, and the refolding yield reached 100% in 18 h. The addition of cold acetone to the reversed micellar solution allowed the recovery of the renatured RNase A without any loss of its activity. In the reversed micellar refolding system, the refolding conditions for inclusion bodies agreed with those for wild-type RNase A artificially denatured with a denaturant. This result indicates that the refolding mechanism of the inclusion bodies is similar to that of the denatured wild-type RNase A. A dilution method for refolding of the inclusion bodies caused the re-aggregation of RNase A, and only 40% of the native activity was regained. Reversed micelles effectively promoted the refolding of RNase A from its inclusion body, suggesting that a reversed micellar protein refolding method can yield a higher rate of renaturation than the conventional dilution method.

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A three-dimensional growth model with cell placement was proposed to express the growth manner of rabbit chondrocytes embedded in collagen gel. This model allows the description of a growth profile consisting of lag and exponential growth phases as well as a stationary phase caused by spatial restriction of cell division (spatial contact inhibition), by considering that the gel matrix is compartmentalized into a set of unit cubes equivalent to the average cell volume, and that the spatial distribution of dissolved oxygen is a limiting factor for growth rate (generation time) of the respective cells. In the cultures conducted at initial cell densities of X₀=1.1×10⁵ and 6.8×10⁵ cells/cm³-gel, the calculated values of cell density based on the model were in fair agreement with the experimental data. Further model analysis was conducted to evaluate the contributions of dissolved oxygen concentration and local cell density to cell division, and it was demonstrated that the effect of spatial contact inhibition become of significance at low cell density in the case of X₀=1.1×10⁵ cells/cm³-gel as compared with X₀=6.8×10⁵ cells/cm³-gel. It was also found that relatively small cell aggregates were interspersed inside the gel matrix when X₀=6.8×10⁵ cells/cm³-gel, whereas the chondrocytes formed larger cell aggregates in the case of X₀=1.1×10⁵ cells/cm³-gel. The proposed model can be a useful tool to estimate the overall cell propagation and spatial cell distribution in the collagen-gel embedded culture of chondrocytes.

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To understand the behavior of the down-flow gasifier for woody biomass, the optimum operation conditions and gasification characteristics were studied. Pulverized wood powder sieved to under by 60 mesh was used for gasification fuel. The CO₂ concentration was increased by 10% by the promotion of oxidation at temperatures above 1600 K. However, total production of CO and H₂ showed little change at around 60%, comprising 40% of CO and 20% of H₂ in the total flue gas. CH₄, C₂H₂ and C₂H₄ were under 5%, 2%, 2%, respectively under the same conditions. Therefore, combustible gas (CO+H₂+CH₄) was over 60%, and the gas-heating value was 5.9-8.9 MJ/m³ N. Carbon gasification conversion and cold gas efficiency reached 90% and 50% respectively at the temperature of 1600 K. Choking of the bag filter by biomass tar was controlled better by injecting on inert absorbent.

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A model of scale growth in the furnace water wall tubes of fossil power plants was constructed as a means to predict scale growth in AVT and CWT feedwater treatment methods and the frequency of chemical cleaning for scale removal. The results of scale growth simulation for sub-critical pressure boilers were in good agreement with conventionally measured data, confirming the suitability of the model presented. Consequently, it was found that the chemical cleaning interval for CWT could be extended by about 2.5-3 times compared with AVT. In the case of super-critical pressure boilers, it was predicted from measured data up to 70,000 h for CWT that scale thickness would reach a point requiring chemical cleaning at 200,000 h as opposed to about 25,000-40,000 h for AVT, indicating that the chemical cleaning interval could be extended by about 5-8 times.

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Application of an energy storage system to the LNG vaporization process can level the variation in cold energy generation rate arising from daily and seasonal fluctuations in natural gas consumption, thereby promoting LNG cold energy utilization. In order to commercialize a BOG (Boil-off Gas) re-liquefaction process with a cold energy storage system, we have conducted liquefaction tests for LNG two-phase flow by melting solidified n-pentane as a PCM (phase-change material). Using a latent heat storage unit with finned tubes of similar length to those in a commercial plant, we investigated the overall performance of the storage unit and the heat transfer characteristics around the finned tubes. As a result, LNG and PCM phase change processes were clarified inside and outside the tubes, respectively. Liquefaction time of BOG in the storage unit was approximately in inverse proportion to the duty of the unit, but it became shorter with the increase in the duty since it was more influenced by PCM solid remaining near the outlet of the storage unit. Furthermore, the thermal conductance of the finned tubes of the storage unit was estimated by using the correlations for heat transfer reported in previous studies.

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Vacuum heating separation is one of the methods for removing insulation oil from used pole transformers. In this method, the insulation oil and PCBs are removed from the pole transformers by vaporizing them under vacuum at 200°C, and a high removal performance is achieved without deterioration of the insulation oil, PCBs and pole transformers. However, a long heating time is required to detoxify the pole transformers, because they are heated by radiative heat transfer under vacuum. The purpose of this study is to reduce the heating time of the vacuum heating separation method by means of heat transfer numerical simulation. The simulation results clarified the influences of operating conditions such as the number of plates, pressure in the furnace, heating temperature and heating rate on the heating time of the method.

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Vacuum heating separation is one of the methods for removing insulation oil from pole transformers. In this method, the insulation oil and PCBs are removed from the pole transformers by vaporizing them under vacuum at 200°C, and a high removal performance is achieved without pyrolyzing the insulation oil, PCBs and pole transformers. However, it takes a long time to detoxify pole transformers, because they are heated by radiative heat transfer under vacuum.
The purpose of this study is to make the vacuum heating separation method more efficient by using a vibration dryer. This new method can reduce not only the treatment time, but also running cost. It was estimated that the heating time could be shortened to 48-50% and the space required reduced to 84-88% in comparison with a conventional plant.

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The outlet fluid temperature of a latent heat thermal energy storage unit was numerically estimated using a simplified three-dimensional heat transfer model. In this model, thermal conductivity of liquid phase assumed to have a high value, while free convection heat transfer in the liquid phase is neglected. Comparison of calculated and experimental values showed that the simplified model was able to predict the outlet fluid temperature, which was independent of the thermal conductivity of the liquid phase when the thermal conductivity exceeded a critical value. Moreover, fluid dynamics and heat transfer around heat transfer tubes were numerically predicted using a two-dimensional model that takes into account the free convection heat transfer. Comparison of the numerical results given by the two models showed that the simplified model is applicable to energy thermal storage in which free convection dominates the heat transfer rate.

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The ability of calcined bauxite to enhance water retention of soil was examined by measuring water-retention curves of calcined bauxite, Toyoura sand and laterite soil. Drying rates of mixtures of calcined bauxite and laterite soil and calcined bauxite and Toyoura sand were also measured.
Bauxite calcined at 700°C in a muffle furnace for 1 h could absorb about 30 wt% of water relative to the weight of the bauxite. The water-retention curve of the calcined bauxite indicated that water content gradually decreased with increase in pF up to 4.5, and the maximum slope was at pF=5.5. Therefore, the calcined bauxite can enhance the water retention of both Toyoura sand and laterite soil. The pF changes of the samples during the drying experiment showed that the drying rate of laterite soil decreased at pF values higher than 5.0 on mixing it with calcined bauxite. For the mixture of bauxite with Toyoura sand, the drying rate became smaller than that of the sand alone at pF values higher than 3.5, indicating that the mixture of calcined bauxite with Toyoura sand was more effective than the laterite soil-bauxite mixture.

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We experimentally investigated the effects of airflow rate on the specific growth rates of a blue-green algae, Spirulina platensis, and a green algae, Chlorella pyrenoidosa. For cultivation of C. pyrenoidosa, the specific growth rate was constant when the airflow rate was greater than 5 mL·s^-1. For cultivation of S. platensis, the specific growth rate had a maximum value when the airflow rate was 6 mL·s^-1. We found that an optimal flow rate existed for cultivation of S. platensis and that excess aeration tended to decrease its specific growth rate.

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The use of ultrasonic irradiation was proposed as a means to prevent scale deposition on a heat-transfer surface. A copper pipe was immersed in aqueous calcium sulfate solution, and the mass of calcium sulfate scale deposited on the pipe was measured. A significant amount of scale was deposited when ultrasonic irradiation was not applied, but no scale was deposited when it was applied. It was further found that intermittent irradiation during the period of scale nucleation was effective for the prevention of deposition.

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As a phase-change material (PCM) for high-temperature heat storage at around 80-90°C, D-threitol, which is an isomer of meso-erythritol, was studied to obtain its phase-change characteristics by means of DSC and a lab-scale heating and cooling apparatus. It was found that D-threitol started to melt at around 90°C with a relatively large latent heat of 225 kJ/kg. Upon cooling, D-threitol started to solidify at around 40-46°C and its temperature rose rapidly to 89°C. From these results it was considered that D-threitol is applicable as an environmentally friendly PCM for high-temperature heat storage for hot water supply.

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